The present invention relates to a rechargeable battery, such as a lithium ion rechargeable battery, particularly of a flat shape, which is integrated with a battery protection circuit so that the rechargeable battery itself has a function of protecting against overcharging, overdischarging, and so forth.
Rechargeable batteries are provided with a variety of protective functions for preventing damage to the battery caused by abnormal use such as overcharging, overdischarging, short-circuiting between the positive and negative electrodes, or short-circuiting of the battery peripheral circuitry of the device in which the battery is used. Examples of these functions include PTC (Positive Temperature Coefficient) elements that prevent excessive discharge current due to short-circuiting or the like, and safety vents that release internal pressure by cutting off the power circuit in the event of an abnormal rise in internal pressure caused by overcharging. These protective functions are known as functions incorporated into the rechargeable battery itself. A lithium ion rechargeable battery is normally provided with a battery protection circuit to prevent overcharging, overdischarging, and so forth. Such battery protection circuit is generally unitized with the battery as part of battery pack configuration, in which a circuit board that makes up the battery protection circuit is integrally contained in the pack case along with the lithium ion rechargeable battery. It is common knowledge that battery packs such as this, in which the rechargeable battery and the protection circuit are integrally housed in a case, are often used for battery-powered devices such as cellular telephones and laptop computers.
In addition to preventing overcharging and overdischarging as mentioned above, this battery protection circuit can also have such functions as cutting off excessive current or monitoring cell temperature, and if this circuit could be integrated with the rechargeable battery itself, it would be possible to create a rechargeable battery equipped with a battery protection circuit without constituting a battery pack, which would make the rechargeable battery more universally applicable.
When a battery protection circuit is integrated with a rechargeable battery, however, it is difficult to avoid making the external dimensions larger or losing the original configuration of the rechargeable battery. In particular, a flat-shaped rechargeable battery is made thin so that it can be used in small devices such as portable devices, and when a battery protection circuit is integrated with such a rechargeable battery it is difficult to find space for the circuit board that makes up the battery protection circuit, which means that it is difficult to integrate a battery protection circuit without increasing the external dimensions.
Also, with a small, flat-shaped rechargeable battery, there is little space in which to provide the above-mentioned PTC element or current cut-off vent, so the elements for electromotive force must be reduced in size in order to ensure this space, the problem with which is that the battery capacity is diminished. Therefore a PTC element must be provided as part of the battery protection circuit outside the rechargeable battery, and the battery protection circuit must take over the function of the current cut-off vent. However, if a PTC element is provided as part of the battery protection circuit, then an increase in volume is inevitable when the battery protection circuit is integrated with the rechargeable battery, which is contrary to the objective of minimizing the increase in external dimensions. Also, reliability suffers when an ordinary battery protection circuit is made to take on the function of a current cut-off vent, making it difficult to obtain a level of reliability at which the rechargeable battery will definitely be protected.
It is an object of the present invention to provide a battery equipped with a battery protection circuit, with which a compact construction that can be applied to a flat-shaped rechargeable battery minimizes the increase in the external dimensions of the rechargeable battery, and with which the battery can be protected by enhancing the function of the battery protection circuit and without providing a PTC element or a current cut-off vent, and which can be used by itself as a battery, without a battery pack configuration being required.
To achieve the above object, a first aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing plate for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing plate, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to the protruding terminal, a circuit board which includes a plurality of input and output terminals and constitutes a battery protection circuit, and to which said connection piece is connected at a specific location, and a spacer that keeps the circuit board and the cell case apart, all of which are disposed at one end on the side of the sealing plate of the cell case; and
a cover cap disposed so as to envelop the circuit board, the spacer, and the connection piece in a state in which said plurality of input and output terminals on the circuit board are exposed to the outside, and at the same time to cover the peripheral part of the cell case, said cover cap being connected at a specific location of the circuit board.
With the above structure, the rechargeable battery and the circuit board are electrically connected by the cover cap and the connection piece through the positive and negative electrodes of the rechargeable battery, and are integrated by the cover cap. Because the input and output terminals provided on the circuit board are exposed on the outside, the rechargeable battery with its internally integrated battery protection circuit can be handled and used just the same as a rechargeable battery alone.
In the above structure, the cover cap can be provided so as to cover the entire surface of the peripheral part of the cell case, which securely maintains the integration of the rechargeable battery and the circuit board that makes up the battery protection circuit.
Also, if at least one inward cutout is formed in the peripheral part of the cover cap, this is bent inward to hit the top of the cell case, and at least one opening is formed in the peripheral part after it has been bent, the cover cap will be fixed more securely to the rechargeable battery, and at the same time an opening will be formed communicating with the sealing assembly of the rechargeable battery, thereby forming a gas escape hole for releasing any abnormally high pressure inside the rechargeable battery.
The plurality of input and output terminals provided on the circuit board can be disposed asymmetrically, which prevents the cell from being installed backwards.
The outside of the circuit board can be covered with a cover plate provided with windows that open over the input and output terminals, which protects the circuit board.
If the outer side of the mounting location of an IC disposed on the inner side of the circuit board is at least 0.1 mm away from the cover plate, then the electrical effect caused by the application of pressure from the outside to the IC can be prevented.
If the connection piece is disposed on the protruding terminal of the rechargeable battery, and the underside of the circuit board is supported by this connection piece alone or by both the connection piece and the spacer, then the input and output terminals, which are subjected to contact pressure from the device side, will be supported from their underside, so stable connected is achieved.
If positioning components with respect to the rechargeable battery are formed in the spacer, it will be easier to install the spacer on the rechargeable battery.
If a notch is formed in the spacer at a location corresponding to the cutout formed in the cover cap, this will ensure a gas escape passage communicating with the opening formed by the cutout from the rechargeable battery.
If a conductor pattern connected to a ground potential is formed on at least the outer side of the circuit board at the location where the battery protection circuit (IC) is disposed, then a shielding effect will also be obtained from the conductor pattern, and the electrical effect that electromagnetic waves emitted from the device side would otherwise have on the IC can be prevented.
If the conductor pattern formed directly under the battery protection circuit is connected at a proximal location to a thermistor disposed on the inner side of the circuit board, then the temperature of the IC, which conducts heat through the conductor pattern, can be sensed by the thermistor, and the thermistor that is on the inner side of the circuit board and detects the generation of heat in the rechargeable battery will also be sensitive to the heat of the IC and can be used for temperature sensing of the rechargeable battery and the IC.
If the connection piece is such that the portion joined with the protruding terminal is formed in a thickness corresponding to the.distance between the protruding terminal and the circuit board, and connecting leads to the circuit board are formed at both ends, then the middle part of the circuit board can be supported by the connection piece.
If the side peripheral surface is covered with an electrically insulating sheet, then the side peripheral surface where one of the polar terminals of the cell is exposed will be insulated and covered, allowing unexpected short-circuiting to be prevented.
If a perforated line surrounding the opening formed in the cover cap is formed in the sheet at a location corresponding to this opening, then the opening used for gas escape will not be blocked off, and instead the sheet will tear out along the perforated line during gas release.
If at least one, and preferably all, of the connection piece, the input and output terminals, and the cover cap is or are formed from a nickel-copper alloy, then there will be better compatibility to joining by soldering, spot welding, and so forth, affording better compatibility to the type of joining means used at the connection location.
A second aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to said protruding terminal, a circuit board on which a battery protection circuit is formed and on which a plurality of input and output terminals are formed, and a spacer that forms a seat for the circuit board and keeps the circuit board and the rechargeable battery apart, all of which are disposed at one end on the side of the sealing assembly of the cell case;
a lead plate joined to the cell case, said lead plate and said connection piece being respectively connected at specific locations of the circuit board so that the rechargeable battery and the circuit board are integrated, and the rechargeable battery and the battery protection circuit are electrically connected, with the positive and negative electrodes of the rechargeable battery being connected via the battery protection circuit to said respective input and output terminals of the circuit board;
an upper insulation board disposed on the circuit board with openings formed at locations corresponding to said input and output terminals;
a lower insulation board disposed on a bottom surface of the cell case; and
an insulating sheet for covering the entire side peripheral surface of the cell case between peripheral edges of the upper insulation board and the lower insulation board.
With the above structure, because the circuit board is disposed on the rechargeable battery via a spacer, and the rechargeable battery is connected to the battery protection circuit on this circuit board by the connection piece and the lead plate, the rechargeable battery is formed as a rechargeable battery equipped with a battery protection circuit connected to the input and output terminals formed on the circuit board through the battery protection circuit. By insulating and covering all of this rechargeable battery except for the input and output terminals with the upper insulation board, the lower insulation board, and the insulating sheet, the resulting rechargeable battery equipped with a battery protection circuit has a compact configuration in which just the input and output terminals are exposed on the outside.
A third aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to said protruding terminal, a circuit board on which a battery protection circuit is formed and on which a plurality of input and output terminals are formed, and a spacer that forms a seat for the circuit board and keeps the circuit board and the rechargeable battery apart, all of which are disposed at one end on the side of the sealing assembly of the cell case;
a lead plate joined to the cell case, said lead plate and said connection piece being respectively connected at specific locations of the circuit board so that the rechargeable battery and the circuit board are integrated, and the rechargeable battery and the battery protection circuit are electrically connected, with the positive and negative electrodes of the rechargeable battery being connected via the battery protection circuit to said respective input and output terminals of the circuit board, thereby constituting a rechargeable battery with a battery protection circuit; and
a pack case in which openings are formed at locations corresponding to said input and output terminals for accommodating therein said rechargeable battery with the battery protection circuit.
With the above structure, because the circuit board is disposed on the rechargeable battery via a spacer, and the rechargeable battery is connected to the battery protection circuit on this circuit board by the connection piece and the lead plate, the rechargeable battery is formed as a rechargeable battery equipped with a battery protection circuit connected to the input and output terminals formed on the circuit board through the battery protection circuit. By housing this rechargeable battery in a pack case having openings at locations corresponding to the input and output terminals, the resulting rechargeable battery equipped with a battery protection circuit has a compact configuration in which just the input and output terminals are exposed on the outside.
In the above structure, if the connection piece and the lead plate are connected to the circuit board by a pair of leads, then the circuit board will be supported more securely on the rechargeable battery.
The plurality of input and output terminals provided on the circuit board can be disposed asymmetrically, which prevents the cell from being installed backwards.
The conductor patterns formed on the circuit board can be used directly as the input and output terminals, allowing the cell to be used in a fixed state in which it is not removed the device in which it is used.
The input and output terminals can comprise metal sheets joined to conductor patterns formed on the circuit board, which allows the cell to be used in applications in which it can be removed from the device.
If positioning components for the rechargeable battery and a housing component for the electronic parts mounted on the circuit board are formed in the spacer, then the spacer can be positioned on the rechargeable battery, the thickness of the electronic parts on the circuit board located thereon will be absorbed within the spacer, and the space taken up by the circuit board can be kept to a minimum.
If the spacer is adhesively joined to the rechargeable battery, the circuit board can be positioned and held at the proper location.
The insulating sheet can be formed from a material that is heat-shrinkable and self-adhesive, which allows the constituent elements to be securely enveloped, and a rechargeable battery with an attractive appearance to be formed.
The insulating sheet can have a design on its surface, which provides an attractive appearance and at the same time allows usage instructions, warnings, or the like to be indicated.
If steps for determining the covering position of the insulating sheet are formed around the peripheral edges of the upper insulation board and the lower insulation board, the tail end of the covered insulating sheet can be accommodated within these steps.
A recess for accommodating the lead plate and a recess into which the bottom of the cell case fits can be formed in the lower insulation board, which allows the lead plate to be accommodated and positioned at the bottom surface of the rechargeable battery.
If the battery protection circuit is equipped with a main control circuit and a sub-control circuit for redundantly protecting the rechargeable battery from overcharging, then the rechargeable battery will be redundantly protected from overcharging that could damage it, eliminating the need for other means for preventing excessive current.
The battery protection circuit can be configured as a circuit with no PTC by being a circuit for preventing excessive current, which allows-the battery protection circuit to be more compact.
The configuration of the battery protection circuit allows the rechargeable battery to have no PTC in its interior, and eliminating the PTC makes it possible to increase the volume of the elements for electromotive force and raises the cell capacity.
Since overcharging is effectively prevented by the redundant anti-overcharging function had by the battery protection circuit, increases in the internal cell pressure due to overcharging are prevented, so the rechargeable battery does not have to have a current cut-off vent in its interior, which makes it possible to increase the volume of the elements for electromotive force and raises the cell capacity.
A fourth aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case in the middle of said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a circuit board disposed on the sealing assembly, on which are formed a battery protection circuit and a plurality of input and output terminals, the protruding terminal and the cell case being connected to said input and output terminals via said battery protection circuit;
an upper insulating holder which is disposed at one end on the side of the sealing assembly of the cell case and in which openings are formed at locations corresponding to the input and output terminals;
a lower insulating holder disposed at the bottom of the rechargeable battery, said upper insulating holder and said lower insulating holder respectively covering an upper and a lower parts of the rechargeable battery; and
an insulating sheet for covering the peripheral side surface of the rechargeable battery.
With the above structure, the positive and negative electrodes of the rechargeable battery are connected to a plurality of input and output terminals formed on the circuit board via a battery protection circuit, and the surrounding area thereof is insulated and covered by an insulating sheet and an upper insulation holder and a lower insulation holder provided with openings at locations corresponding to the input and output terminals. A rechargeable battery equipped with a battery protection circuit can be achieved merely by providing enough space for the circuit board to be disposed on the sealing assembly of the rechargeable battery, without losing the original configuration of the rechargeable battery.
A fifth aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case in the middle of said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to the protruding terminal, a circuit board on which a battery protection circuit and a plurality of input and output terminals are formed, and a spacer that forms a seat for the circuit board and keeps the circuit board and the rechargeable battery apart, all of which are disposed at one end on the side of the sealing assembly of the cell case;
a lead plate connected to the cell case, said lead plate and said connection piece being each connected at specific locations of the circuit board so that the rechargeable battery and the circuit board are integrated, and the rechargeable battery and the battery protection circuit are electrically connected, with the positive and negative electrodes of the rechargeable battery being connected via the battery protection circuit to the input and output terminals;
an upper insulating holder disposed at one end on the side of the sealing assembly of the cell case, covering the top of the circuit board, and having openings formed at locations corresponding to the input and output terminals;
linking members formed at the distal ends of a pair of extensions that extend from both sides of said upper insulating holder toward the bottom side of the cell case;
a lower insulating holder disposed at the bottom end of the cell case, covering the bottom of the cell case;
linking members formed at the distal ends of a pair of extensions that extend from both sides of said lower insulating holder toward the side of the sealing assembly of the cell case, the upper insulating holder and the lower insulating holder being-linked together via said linking members; and
an insulating sheet for covering the side peripheral surface of the rechargeable battery including the side peripheral parts of the upper insulating holder and the lower insulating holder.
With the above structure, the circuit board is arranged on the rechargeable battery with the spacer interposed therebetween, and the rechargeable battery is connected to the battery protection circuit formed on the circuit board through the connection piece and the lead plate, whereby provided is the rechargeable battery equipped with the battery protection circuit, connected to the input and output terminals formed on the circuit board. By covering the rechargeable battery by the upper insulation holder, the lower and insulation holder and the insulation sheet with only the input and output terminals exposed to outside, it is possible to obtain a rechargeable battery equipped with a battery protection circuit with only the input and output terminals exposed to outside.
In the above structure, it is favorable for the rechargeable battery to be one with a flat shape having an oval cross section, which can be used as a power source for portable devices that are intended to be small and thin.
The electronic parts mounted at the sealed end of the circuit board can be disposed at locations corresponding to recesses formed in the sealing assembly of the rechargeable battery, which reduces the amount that the battery protection circuit protrudes from the rechargeable battery.
If positioning components with respect to the rechargeable battery and the circuit board, and openings at locations corresponding to the electronic parts mounted on the circuit board are formed in the spacer, then the spacer will be positioned when mounted on the rechargeable battery, the electronic parts mounted on the sealing assembly side of the circuit board will fit in the openings, and the battery protection circuit will take up less space.
If the positioning components are disposed in parallel in the lengthwise direction of the protruding terminal, then insulation between the cell case and the connection piece can be increased at the same that positioning is performed.
The plurality of input and output terminals provided on the circuit board can be disposed asymmetrically, which prevents the rechargeable battery from being installed backwards.
A step for determining the covering position of the insulating sheet can be formed around the side periphery of the upper insulating holder, which allows the insulating sheet to be positioned while being stuck on.
If covering components that cover the short side surface and part of the long side surface of the rechargeable battery formed in a flattened shape are formed for the upper insulating holder and the lower insulating holder, then the rechargeable battery and the battery protection circuit can be securely integrated, and since the upper and lower insulation holders do not cover the entire rechargeable battery, no change in the exterior dimensions occurs even if repeated charging and discharging or the like should cause the cell case to swell.
If the upper insulating holder and the lower insulating holder are linked by the superposition and/or engagement of the linking components thereof, the linking will be more secure.
The lead plates can be joined at one end to the bottom surface of the cell case and extend to the sealing assembly side along the short side surface of the flattened cell case, which does not increase the thickness of the flat-shape rechargeable battery.
If recesses or openings for accommodating the lead plates are formed in the extensions of the upper insulating holder and the lower insulating holder, then the position of the lead plates can be maintained while the increase in width is minimized.
The battery protection circuit can be a redundant protection circuit comprising a main control circuit for cutting off the charging/discharging circuit when a state such as overcharging or overdischarging is detected, and a sub-control circuit for cutting off the charging/discharging circuit when there is malfunction in this main control circuit, and the ground locations of the main and sub-control circuits can be separated, which results in the pair of lead plates, which are connected at one end to the cell case, being connected to the ground locations of the main control circuit and the sub-control circuit, between which there is no direct connection, so a closed circuit is not formed in the ground circuit, and the effect of noise that would otherwise be caused by a closed circuit can be reduced.
A sixth aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a circuit board disposed on said sealing assembly, including a battery protection circuit and a plurality of input and output terminals, wherein said cell case and said protruding terminal are each connected to said input and output terminals via the battery protection circuit, thereby constituting an intermediate unit in which the rechargeable battery and the circuit board are integrated; and
an outer case in which openings are formed at locations corresponding to the input and output terminals for sealing therein said intermediate unit.
A seventh aspect of the present invention provides a rechargeable battery equipped with a battery protection circuit for protecting this rechargeable battery from overcharging and overdischarging, comprising:
a cell case made of a bottomed cylindrical container, containing therein elements for electromotive force;
a sealing assembly for sealing an open end of said cell case;
a protruding terminal provided insulated from the cell case on said sealing assembly, said cell case and said protruding terminal being respectively assigned as a positive electrode and a negative electrode of the rechargeable battery;
a connection piece joined to the protruding terminal, a circuit board on which a battery protection circuit and a plurality of input and output terminals are formed, and a spacer that forms a seat for the circuit board and keeps the circuit board apart from the rechargeable battery, all of which are disposed at one end on the side of the sealing assembly of the cell case,
a lead plate joined to the cell case, said lead plate and said connection piece being each connected at specific locations of the circuit board so that the rechargeable battery and the circuit board are integrated, thereby constituting an intermediate unit in which the rechargeable battery and the battery protection circuit are electrically connected, with the positive and negative electrodes of the rechargeable battery being connected via the battery protection circuit to the input and output terminals of the circuit board; and
an outer case in which said intermediate unit is inserted, said outer case being molded by resin molding in the form of a bottomed cylinder having an open end, with openings formed in the bottom surface at locations corresponding to the input and output terminals of the circuit board, said open end of the outer case being closed to seal the intermediate unit within the outer case.
With the above structures, the circuit board having the battery protection circuit is disposed on a sealing assembly of the rechargeable battery via a spacer, so the battery protection circuit can be connected to the rechargeable battery with only a minimum of increase in rechargeable battery height, and sealing this rechargeable battery in an outer case provided with openings at locations corresponding to the input and output terminals allows a rechargeable battery with a compact, integrated battery protection circuit to be produced.
In the above structures, the outer case can be such that the cross sectional outer shape is formed substantially oval with respect to the rechargeable battery that is formed in a cross sectional oval shape, and the inner shape is formed substantially oval corresponding to the outer shape of the rechargeable battery, the result of which is that the rechargeable battery equipped with a battery protection circuit has a rectangular shape that facilitates installation in a device, and at the same time the strength of the outer case is improved.
The outer case can also be such that sealing pieces that are extensions of the long side peripheral parts are formed at the open end of a bottomed box, these sealing pieces are bent inward and the opposing parts are fused together by hot pressing, thereby closing the open end and sealing the intermediate unit within the outer case, the result of which is that the intermediate unit can be sealed by a one-piece outer case.
It is favorable for the sealing pieces[2] to be such that the opposing long sides at the rectangular open end are formed in a notched shape so that the notches will fit together when the sealing pieces are bent, the result of which is that the fused mass is increased and sealing strength thereby improved.
The sealing pieces can be formed thicker at the fused portions thereof, which provides enough resin to be melted and makes more secure fusion possible.
If the sealing pieces are sized such that a gap is left between the opposing parts when the sealing pieces are bent, then there will be no overlap of the opposing pieces due to bending error, and the molten resin will work its way through the gap into the interior, filling in any gap resulting from dimensional error in the intermediate unit and absorbing the error.
If bumps are provided to the inner surface of the sealing pieces, then any gap resulting from dimensional error in the intermediate unit will be filled in by the bumps, allowing looseness to be prevented.
The outer case can be such that sealing pieces that are extensions of the side peripheral parts are formed at the open end of a bottomed box, and after the intermediate unit has been inserted, these sealing pieces are melted inward by hot pressing, thereby closing the open end, in which case the open end side of the intermediate unit, where the extended sealing pieces have been melted and inserted on the inside, will be filled in and this open end closed. Even if there is an error in the height of the intermediate unit, the outer case can be brought to the specified height by changing the amount of molten resin that flows into the gap in the outer case.
The plurality of input and output terminals can be disposed asymmetrically, which prevents the rechargeable battery from being installed in a device backwards.